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           /* 
             九九乘法表:双重for循环

             *
             **
             ***
             ****
                     
             i    num(j 的最大值)
             0     1
             1     2
             2     3
             
             i + 1 = num
        */
        let star = '';
        for (let i = 1; i < 10; i++){
          
            for (let k = 1; k < i + 1; k++){
                star = star + ( i + "*" + k + "=" + i * k) + " ";
                
            }
            
        star = star + '\n';
        }
        console.log(star);
        alert(star);
        
     
        


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